The present invention relates to an air supplying apparatus for an internal combustion engine and, more particularly, to an air supplying apparatus having a supercharger.
A supercharger for supplying pressurized air to an air intake channel of an internal combustion engine such as a gasoline engine is generally driven by a crankshaft of the engine or by the energy of an engine exhaust gas stream. The supercharger of this type can supercharge the engine across an entire range of engine operating conditions from low rotating rate and low load operation to high rotating rate and high load operation.
However, the operating conditions of the engine are constantly changing. If the supercharger is always operated across the entire range described above, output power loss may caused.
For this reason, a supercharger control valve is conventionally disposed at the upstream side of a throttle valve in the air intake channel. A supercharger channel is attached to the air intake channel by a by-pass at the supercharger control valve. In particular, an air pump which acts as the supercharger is disposed in the supercharger channel and the supercharger control valve is interlocked with the throttle valve through a rigid link mechanism so that the supercharger control valve is closed when the throttle valve is opened. In this manner, if the throttle valve is closed or slightly open, the supercharger control valve is opened, whereby supercharged air flows back to the upstream side of the air intake channel and supercharging is substantially interrupted. However, if the throttle valve is fully or substantially opened, the supercharger control valve is completely closed. As a result, proper supercharging is performed.
Since the throttle valve and the supercharger control valve are connected through the rigid link mechanism, any trouble occurring in one valve is directly transmitted to the other valve. Although the supercharger can be operated in a desired operating range of the engine as described above, this new problem is presented.